Liquid and gaseous anhydrous fertilizers are often introduced into the soil by slitting or plowing the soil to a predetermined depth and dispensing the fertilizer immediately behind the plow or knife. Rollers or other back fill apparatus usually follow the plow to close the formed slit and the subsoil dispensing of the fertilizer effectively introduces the nutrients at the location desired.
A number of configurations and designs of subsoil aerators, blades and plows have been proposed and typical examples are shown in U.S. Pat. Nos. 2,439,743; 2,619,054; 2,684,617; 2,849,970; 3,259,087; 3,919,951; 4,033,271; 4,132,181 and 4,201,142.
Existing apparatus for introducing fertilizer within the subsoil are usually fabricated of sheet metal or plate, including welded fabrication, and such apparatus wears quickly, requires frequent replacement, and does not provide complete protection of the dispenser tube.
It is an object of the inventon to provide an anhydrous knife for the subsoil dispensing of fertilizer wherein the knife comprises a long wearing body of cast metal.
Another object of the invention is to provide an anhydrous knife of cast metal wherein a dispensing tube is integrally cast within the material of the cast body.
A further object of the invention is to provide an anhydrous knife of cast metal construction which is of such configuration as to reduce the energy required to pull the knife through the soil and provide optimum wear resistance at those locations wherein maximum abrasion and wear occurs.
Yet another object of the invention is to provide an anhydrous knife of cast metal construction which is economical to produce, protects the injection orifices of the dispensing tube, and which quickly closes the slit defined in the earth to retain the deposited material.
In the practice of the invention, the anhydrous knife consists of an elongated body cast of metal, preferably a ductile iron, such as bainitic ductile iron, which is hardenable. The upper end of the body includes an attachment end defined by holes receiving bolts permitting the knife body to be detachably mounted to the carrier. The body central region includes a sharpened leading edge, and the lower end of the body is of an enlarged streamlined configuration defining a sacrificial metal mass having long wearing characteristics. The mass at the toe end of the body includes a trailing edge having recesses defined therein into which the dispensed material is injected. In this manner, the toe end mass protects the orifices of the dispensing tube.
A dispensing tube is integrally cast into the body configuration extending the length thereof. As the body material completely surrounds the tube, the tube is fully protected against damage from rocks and the like within the soil, and the lower end of the tube includes orifices communicating with the recesses defined in the toe end mass which are protected from direct engagement with a solid soil face.
A generally planar projection is homogeneously defined on the body extending from the trailing edge thereof, and is of such configuration and location as to immediately close the slit defined in the soil by the body as it moves therethrough. This "backfill" projection directs displaced and adjacent soil into the formed soil slit immediately after introduction of the fertilizer thereby retaining the fertilizer in the soil and insuring maximum utilization thereof. The backfilling and soil compacting projection is of a generally planar configuration obliquely oriented to the direction of knife movement to compress and compact the soil after being penetrated by the knife.